Process for the electrolytic manufacture of metal tubes.



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OTTU lllfltllil lfiithallli. (NF Drtltltiid'klllll, i'll-tllitlrtl ilii Etpecification of Letters Patent.

Patented April 1D, 1906.

Application filed January 9, 1906. Serial No. 295,320.

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Be it known that l, U'r'ro DIEFFENBACII,

" doctor of philosophy, professor at the Tech nical High ESchool of Uarmstadt, and a resi dent of 8 l-liigelstrasse, Darmstadt, in the birand Duchy of Hessen, German Empire, have invented new and useful improvements inll rocesses for the Electrolytic Manufacture of Metal Tubes and other Bodies, of which the following is a specification.

The process for the production of-iirmly adherent smooth galvanic deposits forming the subject of German Patent No. 125,404.

. is based on the addition to the bath liquor oi solid or liquid bodies such as will exert no chemical action and which are capable when usu'iiiciently active movement is imparted to the liquid by impinging a ainst the cathodes both of removing the small bubbles of hydrogen which adhere thereto as well as of smooth ing the metallic deposits. The specification mentions sand, umice stone, brickdust,

&c., as being solid sub-' stances suitable for the purpose. In some cases, however, these substances only effect their object in an imperfect manner. For example, if when using such additions as are designed to smooth the deposits it is at tempted to produce copper tubes-or other hollow bodies of copper. b depositing the copperupon suitably-aha e cathodes revolving on a horizontal or inc ined axis it is found that none of the substances cited are capable of effecting a sui'licient smoothing action.

" hand, pumice-stone, brick-dust, and so on,

' even when in the finest state of division, are

too heavy to be sufficiently raised by the rotation of the cathodes, especially when the cathodes have a large peri 'hery. Other bodies, such as wood-fiour an so on, float on to of the liquid by reason of: their small speci 0 weight, and for this reason they will not serve for coating the rotating cathodes to the required extent. Furthermore, these-bodies are not sufficiently fine and sharp-edged to cut up, and therebyremove, the small bubbles .of hydrogen which are deposited on the surface of the metal and to the presence of which the formation of uneven deposits is chiefly due. i

It is only possible to expect a perfectly smooth and uniform deposit when the-added substances have a very fine granular texture and sharp edges and are of a nature such that they will be readily carried up by the rotary movement of the cathode on one side and ments that the only substance capable of in]- filling all requirements in a perfect manner is comininutcd lrieselguhr, which by reason oi its iine ly-porous nature becomes strongly inn'negnated or saturated with liquid, with the result that the specific. weight of its smallest particlcs considerably reduced as com pared with that oi other substances, such as sand and puinicestonc, which are not much heavier per se, but have a far smaller capacity for absorbing water.. Consequently by the rotation of the cathodes it is carried up much more readily than the other substances referred to,while, on the other hand, it is heavy enough to be carried down again on the'other side. Especially as regards pumice-stone, which is nearest to it as regards specific weight, lrieselguhr has the further advantage of being much harder and sharper-edged, so that it is capable of cutting up, more readily than pnmiee-stone, the small bubbles of l1ydrogen that are deposited on the cathodes. Yetnotwithstandingthis greater hardness it is less brittle, and therefore more durable than pumice-stone. Whereas the latter is gradually broken u a by the frequent impact against the hard metal surface into a gradally increasingly finer powder, which finally becomes absolutely useless, especially as its several grains become rounded by rubbing against one another, hieselguhr, by reason of its greater strength and toughness, undergoes only an inconsiderable amount of breaking has been demonstrated by means of comparative tests relating to the strength of the different kinds'of copper tubes, from which it has been seen that the tubes produced in accordance with the herein-described process were superior as regards strength to all others. A further advantage of this process is that it can be employed without difficulty for the manufacture of tubes of any desired dimensions, whereas when mechanical smoothingtools are used the difliculties increase, especially withlincrease of length, because the reat pressure of the smoothing tools easily a 1 gives rise to deflections.

With the same success as in the manufacture of tubes or other hollow bodies of copper the herein escribed process may also be utilized for the manufacture of similar articles of nickel and other metals. Likewise instead of using the process for the manufacture of deposits which are separated from their foundation after the completion of the electrolytic operation the process may also be used for producing permanent metal deposits upon metallic or non-metallic bodies *Which are caused to rotate on a horizontal or an inclined axis, itbeing understood that air e19 The process of producing galvanic deposits, which consists in mixing comminuted kieselguhr with a suitable electrolyte, passing an electric'current through the mixture and simultaneously producing. a relative movement between the electrolyte and the cathode vto dislodge the hydrogen bubbles'and to smooth the metallic deposit by the action of the kieselguhr. In testimony that I claim the foregoing as my invention 1 have signed my name, in presence of 'tWo' witnesses, this 27th day of December, 1905. r I

y OTTO DIEFFENBACH. Witnesses r ROBERT BRiinL, i I JEA GRUND. 

